


The Mark of Caine: An Undertale Fanfiction

by Siege_Machine



Category: Undertale (Video Game)
Genre: Gen
Language: English
Status: Completed
Published: 2018-12-23
Updated: 2018-12-23
Packaged: 2019-09-25 07:19:03
Rating: Teen And Up Audiences
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 3,682
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/17116907
Author URL: https://archiveofourown.org/users/Siege_Machine/pseuds/Siege_Machine
Summary: This story follows the adventures of a bounty hunter named Caine, an AU version of Sans the skeleton, who exists as an anomaly and has a sad, warped past that continues to plague him. While hunting Cross, AKA XTale!Sans, he soon realizes that he himself is being chased after by several other monsters. He also meets a lost girl who seems to be the only one to understand him and capable of helping him to battle his inner demons. Much of Caine's backstory is explained, all while he continues his trek for adventure, answers, and treasure, all leading up to a confrontation with his most dangerous and powerful enemy yet.





	The Mark of Caine: An Undertale Fanfiction

**Prologue**

“W-Well, that’s not what I expected...”

_No. Not again._

“But… st… still! I believe in you!”

_For heaven’s sake, not again._

“You can do a little better!”

_P-P-Papyrus!_

“Even if you don’t think so!”

_Don’t leave me again!_

“I… I promise…”

_NO!!!!!!!_

 

**Chapter I: Burning Sensation**

Grillby’s was nearly empty tonight, save for a couple of dog guards and the two town drunks, the ugly fish and red bird. There was also a cloaked figure sitting at the table, guzzling down a red liquid of some kind. One of the drunks lazily gazed over towards the mysterious individual.

“Whatcha havin’ there, pal?” he asked.

“Ketchup,” replied the stranger.

The other drunk joined in. “Hey, hey, there’s another guy who likes to do that. Remember? The… the skeleton guy, yeah!”

“Which one, ya moron?! There’s two of ‘em.”

“Ya know, the short, fat one.”

“Oh, yeah. That dude. Sans, right?”

Shadows crept over the stranger’s round face. He sat the ketchup bottle down with a _thunk_ , but the rest of his body, his face included, remained motionless. “I’m not Sans.”

The red bird narrowed his eyes, in an attempt to analyze the newcomer. “Hey, now that I got a betta’ look at ‘cha… you DO look like Sans the skeleton!”

“Looks can be deceiving. It’s only the crap on the inside that makes any difference between one monster and another. And believe you me… Sans and I are two very different individuals.” He held up the ketchup bottle and looked towards Grillby. “Hey, this stuff isn’t potent enough. Got anything with more of a kick?”

Grillby slid a bottle of hot sauce down the table. The stranger immediately unscrewed the cap and sipped some of it. Then he violently shook the bottle to make it fall faster out of the bottle and down his throat. After the swigging session, he put down a few gold on the table. Only after he got up to leave did Grillby move forward to collect his pay. The flaming bartender knew to keep his distance from someone like that.

“What’s wrong with the ketchup?” asked the inebriated fish. “Maybe barbeque sauce would’ve better suited ya.”

“It doesn’t taste the same anymore. Too dull,” replied the monster, who immediately raised the hot sauce bottle. “But this baby? Well, let’s just say that the burning sensation enhances the flavor. Pain gives it that kick I need.”

With that, the newcomer sauntered out of the bar. The canine soldiers sniffed in his direction, all of them detecting something suspicious about him. The smashed bird flopped his head towards Grillby.

“Hey, Grill-meister, who in the Underground was that crackpot?”

Without saying a word, Grillby grabbed a piece of paper and a pen, and wrote down five letters on it. Then he slid the paper towards the stoned customer.

“C… A…I…N…E…” he read drowsily. “Caine. Huh, what an odd name.”

Outside Grillby’s, Caine pulled up the long coat flaps around his neck and wrapped the long robe-like jacket around his skeletal body. He took another glug of hot sauce, then packed it away in his inventory for later. The cold snow was starting to engulf his black and emerald green slippers. The external freezing temperature hitting against his internal burn of hot sauce and heartbreak… it was almost poetic. But he was quite used to such extreme, uncomfortable conditions. A burden was always upon Caine… one that no other living soul knew of. At least, as far as he knew.

Caine’s darkened eyes scanned the area. “If that info was worth any beans, that bonehead should be here… any… second.”

And no, Caine was still not talking about Sans. At least, not this universe’s Sans. No, this was just another run-of-the-mill Undertale timeline in a regular Undertale universe, pre-human interference. The actual Sans was napping somewhere else. No, Caine was searching for a one more dangerous threat… an anomaly, you could say.

A flash of light caught Caine’s eye. And there he was, stepping through the portal, fashioning a knife the size of a doorway. He was completely black and white, except for his right eye and the scar on his right cheek, both blazing red. He pulled his scarf up over his mouth as it blew violently in the wind, and pulled his feathery hoodie over his head.

Caine would have smiled at this moment, except he was always smiling… a lifeless, meaningless smile. But this moment put a flicker of some kind of thrilling emotion inside his hurting soul. He uttered but a single word.

“Cross.”

 

**Chapter II: Crossing Paths**

Caine wasn’t the only watchful one, though. Almost immediately, after taking a few steps forward, Cross froze, having spotted Caine standing a few feet in front of Grillby’s. But stealth wasn’t Caine’s objective in hunting down this bounty. He knew this would happen. In fact, he had been counting on it.

“Good evening, Subject Number 5972,” stated Caine, “also known by the aliases XTale!Sans and Cross. You are wanted in several alternate universe, and I am here to arrest you so that you may be tried for your many egregious crimes in front of a council of elders.”

“Who the heck do you think you are?” asked Cross, narrowing his eyes.

“If you do not come along peacefully, I am afraid I will have no choice but to incapacitate you with force.” Caine’s eyes glimmered. “Although, it would be much more fun if you did try to resist.”

Cross’s eyes looked sideways, appearing as if he were looking at someone or something. Then they flashed back to meet Caine’s dead-faced stare. “So, you’re a bounty hunter, huh? Welp, there’s plenty of other universes and timelines to harvest resources from. I’ll just take my leave.”

“Don’t you mean ‘we’ll be taking our leave?’” corrected Caine. “Hello, Subject 5971, also known as XTale!Chara. I cannot see you, but I know you’re there. I’ll be bringing both of you into custody.”

“Frick,” Cross muttered. Suddenly, a portal opened up behind him, which took him slightly by surprise. He hesitated for only a second, but that second was enough time for Caine to dart towards Cross and tackle him into the portal. Lights flashed all around the two as they struggled against each other, flying through the code of the multiverses, collectively known as the Underverse. After a few seconds, they arrived at a destination: a blank, white void.

The void was not completely empty. A few houses, trees, and other random items were strewn around the area. This empty place was once where the XTale universe existed, but it was all destroyed as a clash between two powerful forces.

Caine knew all this stuff already from the file he read, but it was just meaningless history to him. All he cared about was hunting down Cross, who had been stealing source code and resources from other alternate universes. He had caught the attention of several other higher beings that acted over overseers of the Underverse. A bounty had been placed on Cross’s head, and bounty-hunting was what Caine was all about.

As the portal closed off behind them, Cross shoved Caine off him, then darted away. Caine brushed off his jacket, and began pursuing his foe on foot at an incredibly fast pace, especially for an AU Sans. Before long, Caine, still wearing that eerie smile, was running next to Cross. The ninja-outfitted skeleton teleported away before Caine could land a blow, now standing on top of a stolen Underfell house.

“What is it that you want from me?” asked Cross, with a mix of anxiousness, confusion, and curiosity upon his face.

“I want to deliver you to the custody of justice,” stated Caine plainly. “There’s something I can get out of this gig, something I need very badly. But hey, buddy, you shouldn’t be too scared, since you’ll still be alive after I’m done with you. I kill most of my targets.”

“Is that supposed to scare me?” smirked Cross. “You’re hardly intimidating, you know. I mean, just look at yourself. Yeah, you got a neat coat and pair of closed slippers that you probably stole from somewhere, to hide a grungy tank-top, filthy sweatpants, and green stuff smeared on your face...”

“You’re one to talk, with your bloodshot right eye and the bloody red lightning bolt on your cheek. Oh, and by the way, these? They’re tattoos.”

“How do you get tattoos on bone?”

“It’s kind of like etching. I know a guy.”

Cross squinted, examining the face markings on Caine, who stood on the ground below the house. “Your left cheek has a teardrop. And your right cheek… it says… wait...” Cross choked for a moment, then finally uttered the name: “... ‘Papyrus.’ ”

“Yup. It’s a long unpleasant story, not too much unlike your own. Let’s just say I know a thing or two about losing your home and friends.”

Cross’s eyes gained an empathic light. “Is that all you lost?”

“Nope. I lost a good bit of my sanity, too. Oh, and my heart is cracked.”

Caine’s soul became visible as it appeared in front of his chest. It was an average Sans soul, colored white and sitting upside-down, but it had a clear, glasslike split that went straight through the middle of the soul. It disappeared as soon as it appeared, only allowing Cross to take a glimpse at it. But it was quite enough of a look for him. He could feel his own broken heart beating inside him, half-monster and half-human, jammed together to keep Cross and Chara alive inside his being.

“I am very sorry for your pain,” Cross said, sighing heavily.

“Welp, nothing I can do about it now. Oh, hi there.”

Cross looked up to realize he had been fooled again, as Caine delivered a painful jab to the ribs. Caine was so fast that in the three seconds Cross had looked away, he had silently ran up the side of the house to where Cross stood. This was both shocking and surprising to Cross, but now he was truly angry. XTale!Chara, who had been watching from the sidelines up until now, whispering to Cross, pushed his skeleton comrade to take action, and together they unleashed their full might upon Caine.

A Gaster Blaster sent Caine flying away from Cross’s valuable resources, but he flipped midair and landed standing upward. Cross prepared his weapon, ready to face his competitor. His Gaster Blaster fired several more shots at Caine, who merely zigzagged at a frightening speed without slowing down. This Sans had intimidated Cross from the first time he saw his especially dark eyes, but only now did Chara start to feel fear creeping up upon him. Caine had refused to use any of his powers or special attacks, instead choosing to fight with his fists and his lightning-fast speed.

 _He’s holding back_ , stated Chara. _But why?_

Caine soon approached Cross after leapfrogging over the Blaster. But this time, Cross was ready. He made several fast swipes with his knife, which were all dodged by Caine, who uppercutted his skull, launching Cross up higher into the white abyss. This blow dazed the Sans part of Cross, so Chara took full control. As soon as gravity started pulling him downward, he dived nosefirst towards the ground, spinning clockwise faster and faster, with his knife pointed in front of him. This effectively made him into a living drill aimed directly at Caine. However, the smiley trashbag dodged the attack, almost losing his footing in the process. This moment of unbalance allowed Cross to spin around his knife planted in the ground and send a horizontal kick right into Caine’s abdomen area. The two went tumbling, and then they kept punching and shoving each other in order to stand up.

Chara knew Cross’s body could stand the blows with the HP provided by the human half of Cross’s soul. Caine, however, was a mystery. How could Caine, with a damaged Sans soul, withstand all these blows? Cross soon got Caine off him, and retrieved his knife. Summoning his Gaster Blaster, he jumped off this weapon like a springboard and drew his knife in front of him. Caine narrowly dodged it, leaning backwards without falling down. Yet, this had all been a distraction. As Cross passed over Caine, his eye lit up, and he flicked his finger subtly.

_CRACK._

Caine tried to stand back up, but found himself permanently locked in an uncomfortable backwards leaning position. He was only slightly surprised to find a long, sharo, spearlike bone had impaled his chest, with blood flowing out. Yet, his facial expression never changed. With several grunts, he grabbed onto the bone with both hands and pulled his body forward, and he eventually slid off the sharp spike. He almost fell over, but he placed a firm foot forward to stabilize himself. The whole time, Cross looked on in terror and rage. The Sans inside him had awaken, and both he and Chara were shaking nervously.

 _A killing blow like should have destroyed him immediately!_ Chara howled. _I heard his soul break apart!_

“I did, too, kiddo. That’s… that’s totally screwed-up.”

The hole in Caine’s middle repaired itself, as the broken bones simply rebonded back together again, and the red blood spewing out of him seemingly vaporized away. Even his clothes mended themselves.

Before he knew what had happened, the traumatized Cross found himself in a headlock. Caine threw away the knife with his other arm and then pulled something out of his jacket pocket. It was only two pieces of rope, but they had a golden shine to it. He jerked Cross’s arms to place them behind his back, even as he feebly squirmed. The ropes were quickly tied into knots around Caine’s hands and ankles. With this, Caine got off Cross and stood next to him, tilting his head.

“Determination-infused rope,” Caine commented. “Some of the strongest stuff you’ll find in the Underverse. Go ahead, try to break it. Here’s a hint: you can’t.”

“Doesn’t matter,” shrugged Cross. “My HP is super-low. I’m not going to do anything stupid.”

“Sorry it had to go down like this, pal.”

“Whatever. Just take me to your bosses.”

“I’m freelance. I don’t have bosses.”

“Oh, please, there’s always a bigger fish. Admittedly, even I am taking orders from someone at the moment. But just for a little while, so I can fix this place up.”

“Doesn’t look like much more can be done for this void.”

“So I’ve been told.”

“Who are you taking orders from?”

“Big, black, scary guy. I don’t even think you could handle him.”

Suddenly, Caine found himself enwrapped in blue string, and was quickly pulled backwards into another portal. This portal created loud, distorted, garbled sounds...

… And it was very glitchy.

 

**Chapter III: No Strings on Me**

Caine awoke to find himself hanging in midair. For a moment, he thought he was falling in an endless limbo, until he felt a slight soreness in his arms. This brought his attention to the glowing blue strings tied around his arms, extending upward into a thick, mesh of blue webbing contrasting against a blood orange sky. He examined his surroundings. There wasn’t much more than orange clouds, an evening sun, and an empty wasteland.

A distorted voice rang out. “I’m s-s-sorry to have interrupted y-y-your spat with C-c-cross earlier.”

Caine tried to shrug with his arms tied up and spread out in a T-pose. “I mean, I would have preferred a heads-up before being literally dragged here, but it’s fine, I suppose. Cross isn’t going anywhere anytime soon.”

“Haha. Y-y-you’re certainly more p-p-polite than most of my guests.”

“Hey, I’m just clocking in the hours. A surprise meeting is always appreciated. Error!Sans, I presume?”

Error teleported to stand in front and below Caine. He gently loosened a string in his hand so that Caine was lowered until he was only a couple feet above the ground, and almost eye-to-eye with Error.

The black, glitching skeleton with blue strings coming out of his eyes smiled wide. “Nice to m-m-meet an admirer.”

“Hey, let’s not get intimate now. I just memorized your file. Business stuff, ya know.”

“Is that w-w-what you’re all about? Business?”

“Yeah, and I was in the middle of it when you caught me. Now, what is it that you need of me? Or were you just protecting your minion from getting served justice?”

“Cr-cr-cross? My m-m-minion? HAH! Hardly,” Error declared with a strange, backwards-sounding echo amplified his voice. “Actually, I’ve been trying to d-d-delete that pesky b-b-bug for a while. He’s under someone else’s protection though, for the moment. However, you seem like you’d be the perfect one for a good deletion. After all, you’re just as much an anomaly as Cross.”

Caine’s face remained stoic. “Welp, you’re not wrong. But at least I’m not trying to cause trouble.”

“Hmm, that m-m-makes no difference to me. You’re not s-s-supposed to exist. You have a br-br-broken Sans soul, and y-y-yet you seem to have alarmingly high HP. And the j-j-jumping-through-universes shenanigans… that’s highly-frowned upon in the Under-der-derverse. Something’s wrong with your-your-your code.”

“Nothing’s wrong with my code. I just made a few tweaks to it so that it would be compatible with some new code I added in. Albeit, it’s not the most efficient stuff, but it gets the job done.”

Error’s eyes widened. “Y-Y-YOU changed your own code? Hah. A l-l-likely story. You hardly seem as p-p-powerful as Ink or Dream.”

“That’s because I only use about thirty-five percent of my capabilities.”

“Now, w-w-why would you do a thing like th-th-that?”

“To make things more fair. I mean, if I really tried, I could wipe out half the multiverse within a day.”

“B-b-big talk for a monster with a broken s-s-soul.” With that, Error pulled the first wire, raising Caine higher, and then tugged on another wire, causing a soul wrapped in Error’s cables to protrude from Caine’s chest. Caine looked down to see it, then quickly refixed his eyes on Error. The bounty hunter’s cheeks actually compressed a little bit, and his usually unmovable grin actually grew larger, if only slightly.

Caine uttered a small chuckle. “Heh, heh, heh.”

Error’s eyes glowed with disturbed glee. “W-w-with one small-small-small tug, I could shatter-er-er your soul.”

“I’d love to see you try.”

“W-w-well, if you INSIST!” exclaimed Error as his voice became demonically dark and low.

With a forceful pull, the string tightened around Caine’s soul, which immediately broke into two with a cracking sound. Pieces of blue string went flying everywhere, as Error anticipated a second cracking sound, which should be followed by Caine dusting away. And yet, Caine just hung there, his soul in two pieces, smiling at Error as if nothing had happened. Then, a golden glow emanated from Caine’s soul, followed by a new sound… the sound of determination. Just like that, the skeleton’s soul was fused back together, still retaining the crack that it had earlier.

Error’s jaw hit the floor. “Imposs-poss-possible.”

Caine shrugged. “Actually, this happens more often than you’d think. Every five seconds, in fact. See?”

On cue, Caine’s white soul broke into two pieces again, and then mended itself again. Then, the soul floated back into Caine’s chest.

Error’s hateful gaze turned into one of confusion. “You’re-you’re-you’re one of the im-mor-mor-mortals?”

“Yes and no. I’m actually constantly dying. But then, this determination stuff puts it back together. It’s kind of like an accordian, being pulled apart and then pushed back together, over and over again.”

“How c-c-can you withstand so much-much-much pain?”

“By being hurt so many times until I went numb. Until I lost all emotional and sensory functions. Pain courses through my body all the time. I had no choice but to live with it. I mean, I can’t stop it by committing suicide, can I now? I’m immortal, but only on a technicality.”

Error stroked his chin. “Although I should be jeal-jeal-jealous of you, I instead pit-pit-pity you.”

“Honestly, you should be afraid. You could have a million ways to kill someone… but how do you kill the unkillable?” Suddenly, several cracking and popping sounds came from Caine, who dropped to the ground… with no coat and no arms, just blood trickling out of his arms sockets.

Error took a few steps backwards. “Y-y-you’d break your own body to try and-and-and kill me?”

“It’s just pain. They’ll regrow in five seconds.”

But Caine didn’t wait. He ducked under Error’s blue-wire whip and roundhouse swept the black skeleton’s legs. Error fell down with a thud, then looked up to see Caine pinning him down with his newly-regenerated arms.

Error slowly shook his head. “You can’t-can’t-can’t destroy me that easily, f-f-fool.”

“You’re not on my hit list, buckaroo. This was just a friendly chat, and I’m just your guest, remember? It would be awfully rude of me to try and kill the host. Now, you’re going to send me right back to Cross’s empty hole so I can collect my prize and leave.”

Caine released his hold of Error, who picked himself up and gave a deadly, hate-filled stare at his opponent. Yet, as much as Error despised this version of Sans, he also respected and even slightly feared him. Besides Ink, this bounty hunter was the only other living being to have ever bested Error.

Without further argument, Error gave a swipe of his hand, and the portal opened to the right of Caine.

“My coat, please?”

Error tugged and then released hold of a hanging string, which caused Caine’s coat to flutter down and gently landed on Caine. A pair of skeletal arms also fell, but they disintegrated on impact with the ground.

“G-g-goodbye, bounty-hunter.”

“You can call me Caine. For your sake, however, you better hope you never hear my name again.” He gave a sloppy salute to Error. “Adios, Glitchy.”

“HOW DARE YOU C-C-CALL ME-”

But before Error could finish his stuttered remark, Caine had disappeared through the portal.

 

**Chapter IV: The Broken Ones**

_To Be Continued..._


End file.
